BEACHPORT, AUSTRALIA / RankWire.AI / – Australia has verified the presence of H5N1 bird flu in a long-nosed fur seal found dead at Beachport in South Australia. This marks the first confirmed mammal infection tied to the outbreak on mainland Australia. The authorities announced the lab results after urgent testing of the animal’s samples. The discovery broadens the outbreak’s scope beyond wild birds for the first time on the mainland. Officials noted that they found no signs of a cluster involving other ill or deceased marine mammals nearby.
A member of the public reported the dead seal on August 19, noticing it showed no visible injuries. Initial testing by the state was inconclusive, prompting officials to send samples for additional testing. CSIRO’s Australian Centre for Disease Preparedness later confirmed H5 bird flu in the seal. Beachport is located on South Australia’s Limestone Coast, an area where authorities have recorded infections among wild seabirds. Since H5N1 reached mainland Australia earlier this year, this region has become one of several coastal sites affected.
By August 23, South Australia had logged 194 confirmed H5 bird flu events, with 11 new cases that day. These included infections in greater crested terns, a gannet, a little penguin, a silver gull, and a black-faced cormorant. The state now reports outbreaks as events, which may involve one or multiple animals at a location. Across the country, Australia had documented 298 positive H5 bird flu events by Sunday. South Australia accounts for the largest proportion of these detections.
Mainland outbreak extends beyond wild avians
The outbreak on the mainland started after H5N1 appeared in migratory seabirds in June 2026. Testing later confirmed the virus in native, non-migratory seabirds, including greater crested terns. As a result, authorities observed an increasing number of affected wild birds across multiple states. South Australia also reported a mass die-off involving over 1,000 greater crested terns during August. The circulating virus in Australia belongs to H5N1 clade 2.3.4.4b, which has impacted wild birds, poultry, and mammals elsewhere in the world.
Despite these wildlife detections, officials have found no H5N1 infections in Australian poultry or other livestock. The Health authorities maintain that the risk to the general public remains low. No locally acquired human cases involving the H5N1 strain from this outbreak have been reported in Australia. Human infections generally require close contact with infected animals or contaminated environments, officials say. They advise avoiding touching sick or dead birds and other wildlife.
Previous H5N1 detections on remote territories
Earlier, Australia confirmed H5N1 in southern elephant seals on Heard Island, a remote Australian territory in the Southern Ocean. Laboratory results verified those infections in November 2025, months before the virus arrived on the mainland. Further testing detected H5 bird flu in other wildlife on the island, including Antarctic fur seals and gentoo penguins. The Beachport case is the first confirmed mammal infection connected to the current mainland outbreak. It is also the first such detection in a native mammal on the mainland.
Authorities continue wildlife surveillance as H5N1 circulates among seabirds along Australia’s coast. They have asked the public to avoid sick or dead wildlife and report sightings. These reports help animal health teams identify new cases and target testing. Monitoring remains active across wildlife, agriculture, and public health sectors as the outbreak unfolds. The confirmed Beachport seal case expands the range of affected species in Australia’s ongoing H5N1 outbreak on the mainland.